Well I recently finished up my third forge and thought I'd share the build with you all as I think it turned out pretty well. Sorry about all the pics, but everybody like pics right!?!?
Back in about 2007, I built a real nice propane gas forge for my very first forge, and while it worked well, I quickly realized that I needed something that could handle a wider piece. So about a year later, I ended up making a simple coal forge from a wheelbarrow tub and a clothes dryer blower. I figured I'd make something simple, quick and cheap... then when I get more experience and could figure out exactly what I wanted in a forge, I could build one specifically to suit my needs. Well I finally went and did it, and I took pictures too! ... Lots and lots of pictures...

To reminisce... here is a picture of my first gas forge, and also my simple wheelbarrow forge.

Now, let's get on with the build!
I've always considered the the firepot to be the heart of the forge, so that's what I started with. I have a CNC plasma cutting table so I drew up the firepot in Corel Draw, then cut out the pieces from 1/4" A36 HR steel and welded it up.

Then I drew up an easy to replace "grate plate" for the bottom of the firpot. I was going to just weld in some bars for the grate, but thought I could easily cut a new one when it gets burnt out, and just drop it in place like this. The extra thickness will help the firpot last longer as well.

I tore apart my wheelbarrow forge and used the blower, tuyere, and ash dump from it since it would save time, and it already worked great. I do wish the ash dump was deeper, but I can live with emptying it more often. I also welded on some bracing straps to mount the blower directly to the tuyere.

I was going to drill and tap some holes in the bottom of the firepot, but I couldn't find my tap and die set, so I figured out which position I wanted the tuyere, drilled some matching holes in the firepot and the flange, then cut the heads off some 3/8" bolts and welded them in place to use as studs instead. I used blue tape to hold the studs upward in place while I plug welded them from the bottom inside of the firepot. Worked great!